*** Updated Sep 16 ***
A bit long winded but here is the guide how to get 22% off any purchase at Halfords.
First get yourself £15.95 Toyota Owners Club Premium membership here (*credit to jamesm182*):http://www.toyotaownersclub.com/membership/
It gives 15% discount for in store Halfords purchases (NOTE - only 10% for bikes).
Or alternatively get yourself a British Cycling £21 FAN membership (£18.90 if paying by DD). Membership gives you 10% in-store discount including Boardman bike range. Ask your friends who might already have it.
Calculate the cost of your purchase after the discount and buy Halfords gift vouchers with 10% discount here:http://select.halfordsbusinessservices.co.uk/
Codes - MCOUNTHal09, ELGHAL13, NRTSCHAL13 - all give 10% off :)
You need to register with the Select site first in order to apply the code. There is £2 delivery charge for Recorded delivery or £7 for RM Special delivery.
In order to purchase more than £300 you will need to keep adding the maximum to your basket, for example add 20 x £10 vouchers to your basket and then go back to the catalogue and add another 20 x £10 vouchers etc.
Many large employers and shopping clubs do have dedicated discount code for the site. You can register with The Big Saving Club, Ideal Extras club, JML (both gives 8% discount though) http://thebigsavingsclub.comhttp://www.myidealrewards.com
Lotus, Escort Cabriolets club members and Morton Michel policy holders also get 10% discount:http://www.seloc.org/membership/benefits/lifestyle/http://www.escortcabrioletclub.co.uk/forums/index.php?/topic/18253-halfords-discount-vouchers/https://www.mortonmichel.com/ChildCareClub/Early-Years-Products/http://www.travelcambs.org.uk/cycle-shop-discounts/
Alternatively you can buy some Halfords gift vouchers at Zeek (usually 8-10% discount) which can be handy for smaller purchases:https://www.zeek.me/buy-gift-vouchers/halfords
Now order your item via Quidco (3%) or TCB (3.03%) and use Reserve&Collect service.
Make the journey to the store once order is available to collect and get your goods :)
This method will work on anything including sale items.
If your payment for gift voucher order is not accepted DO NOT try again. PHONE your bank - they did flag your transaction as fraudulent. Request them to remove the bar then wait at least 30 minutes to an hour before trying again.